From 0eedb5f800381c63f25f96e7753c7b8ccc013a7c Mon Sep 17 00:00:00 2001
From: Rafael Santana <rafaelsantana3095@gmail.com>
Date: Thu, 13 Jul 2017 14:20:16 -0300
Subject: [PATCH] fix(tabs): check if the subscription is defined before
 unsubscribe (#5667)

---
 src/lib/tabs/tab-nav-bar/tab-nav-bar.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/lib/tabs/tab-nav-bar/tab-nav-bar.ts b/src/lib/tabs/tab-nav-bar/tab-nav-bar.ts
index b292b7bf67e..bdd2600ea51 100644
--- a/src/lib/tabs/tab-nav-bar/tab-nav-bar.ts
+++ b/src/lib/tabs/tab-nav-bar/tab-nav-bar.ts
@@ -96,7 +96,10 @@ export class MdTabNav implements AfterContentInit, OnDestroy {
 
   ngOnDestroy() {
     this._onDestroy.next();
-    this._resizeSubscription.unsubscribe();
+
+    if (this._resizeSubscription) {
+      this._resizeSubscription.unsubscribe();
+    }
   }
 
   /** Aligns the ink bar to the active link. */